In the horizontal continuous casting of steel to form steel billets, molten steel is passed horizontally through a cooled mold to cause solidification of the steel. The steel is oscillated back and forth within the mold by the use of an oscillating drive to release cooled solidified steel from the mold wall as it passes through the mold and to remove the cast steel from the mold. The oscillation procedure necessary to remove the cast steel continuously from the mold often leads to surface defects, such as cracks and tears, and to a general surface roughness. These defects do not permit the product to be readily acceptable by a rolling mill.